Frontiers of Knowledge

National Historic Chemical Landmarks Program

Some 2,500 years ago, the Greek philosopher Aristotle postulated that all matter is comprised of four basic elements: earth, water, air, and fire. The idea dominated science until the late 18th century, when revolutionaries from rival nations transformed chemistry from a jumble of medieval alchemy into a true science. The pace of discovery accelerated rapidly as chemists on the frontiers of knowledge established the theories and methodologies of modern science.

Antoine-Laurent Lavoisier: The Chemical Revolution

Académie des Sciences de l’Institut de France | Paris, France

Antoine-Laurent Lavoisier forever changed the practice and concepts of chemistry by forging a new series of laboratory analyses that would bring order to the chaotic centuries of Greek philosophy and medieval alchemy. Through his influential work, Lavoisier challenged the prevailing “phlogistic” theory and demonstrated the true role of oxygen in combustion; he described the role of oxygen in respiration, and showed that water is not an element but a compound comprised of hydrogen and oxygen. Lavoisier’s work in framing the principles of modern chemistry led future generations to regard him as a founder of the science. Learn more.

C.V. Raman: The Raman Effect

Indian Association for the Cultivation of Science | Jadavpur, Calcutta, India

The discovery that earned C. V. Raman the 1930 Nobel Prize in physics was born of an investigation of light sparked by a question a child might ask. Returning to his native India by way of the Mediterranean Sea, Raman wondered about the sea's deep blue color. Dissatisfied with the prevailing explanation—that it reflected the sky—he delved further and demonstrated a universal truth about the behavior of light. In 1928, Raman discovered that when a beam of colored light enters a liquid, it scatters and some of it emerges as a different color. This deceptively simple observation had profound implications. Learn more.

Deciphering the Genetic Code

National Institutes of Health in Bethesda, Maryland

Interpreting the language of the genetic code was the work of Marshall Nirenberg and his colleagues at the National Institutes of Health. Their careful work, conducted in the 1960s, revealed the first word of the genetic code. In the next few years, Nirenberg’s laboratory discovered the codes for all possible combinations of the twenty amino acids. Nirenberg’s work helped pave the way for the mapping of the human genome and for much of recent understanding of the correlations of genetics and disease. Learn more.

Discovery of Fullerenes

Rice University | Houston, Texas

In 1985 Richard Smalley and Robert Curl of Rice University and Harry Kroto of the University of Sussex discovered the first known molecular form of carbon, C60, also known as fullerenes, or buckyballs. Research on fullerenes has led to the synthesis of more than one thousand new compounds, and to advances in the development of carbon nanotubes, which have uses in tiny motors and as ball bearings and lubricants. Fullerenes continue to provide abundant research opportunities in pure chemistry, materials science, pharmaceutical chemistry, and nanotechnology. Learn more.

Discovery of Helium in Natural Gas

The University of Kansas | Lawrence, Kansas

When University of Kansas chemists Hamilton Cady and David McFarland analyzed a natural gas sample in 1905, they solved a local mystery and showed that helium—once thought to be a rare element—was abundant on Earth. Cady and McFarland subsequently analyzed more than 40 other gas samples, showing that helium was available in plentiful quantities from the Great Plains of the United States. Helium-filled blimps were vital to the United States in World War II, and helium is still considered a national strategic reserve material. Learn more.

Edward W. Morley and the Atomic Weight of Oxygen

Case Western Reserve University | Cleveland, Ohio

In his laboratory at Western Reserve University (Now Case Western Reserve University), Edward W. Morley carried out his research on the atomic weight of oxygen that provided an important new standard to the science of chemistry. His analytical techniques earned him national renown, and the accuracy of his analyses has never been superseded by chemical means. His great work, published in 1895, also gave important insight into the atomic theory of matter. Learn more.

Hermann Staudinger and Macromolecules

In 1920, Hermann Staudinger published a paper that postulated that rubber and similar materials are composed of very large molecules that are held together by chemical bonds—the same forces that hold smaller, lighter molecules together. Hermann Staudinger’s pioneering theories on the polymer structures of fibers and plastics and his later research on biological macromolecules formed the basis for countless modern developments in the fields of materials science and biosciences and supported the rapid growth of the plastics industry. Learn more.

Joseph Priestley: Discoverer of Oxygen

Joseph Priestley discovered oxygen in 1774, accurately documenting its properties but explaining his observations in terms of then-prevailing (but soon to be disproven) theory of "phlogiston." An Englishman by birth, Priestley was deeply involved in politics and religion, as well as science. When his vocal support for the American and French revolutions made remaining in his homeland dangerous, Priestley left England in 1794 and continued his work investigating gases in in Northumberland, Pennsylvania. Learn more.

The Keeling Curve: Atmospheric Studies of Carbon Dioxide at Mauna Loa

In 1958, Charles David Keeling of the Scripps Institution of Oceanography initiated a research program for the study of atmospheric carbon dioxide at the newly established Mauna Loa Observatory of the U.S. Weather Bureau. By 1960, Keeling published the results of his research, reporting evidence of Earth’s natural seasonal CO2 oscillations and the annual increase in CO2 as a result of fossil fuel combustion.Today, the continuous record obtained by Scripps and NOAA provide one of the most important scientific linkages between fossil fuel combustion and the rise in global temperatures as a result of the greenhouse effect. Learn more.

Legacy of Rachel Carson's Silent Spring

Chatham University | Pittsburgh, Pennsylvania

Rachel Carson’s Silent Spring, published in 1962, was a landmark in the development of the modern environmental movement. Carson’s scientific perspective and rigor created a work of substantial depth and credibility that sparked widespread debate within the scientific community and the broader public about the effect of pesticides on the natural world. These discussions led to new policies that protect our air, our water, and, ultimately, our health and safety. Learn more.

Moses Gomberg and Organic Free Radicals

University of Michigan | Ann Arbor, Michigan

In 1900, University of Michigan chemist Moses Gomberg achieved what chemists had long believed impossible: He isolated an organic free radical (a carbon compound with an unpaired electron). Gomberg's discovery advanced polymer science, biochemistry, biology and medicine. Organic free radicals are crucial to our understanding of many natural phenomena, including how our bodies synthesize DNA and why some oxidative processes support life while others cause disease. Learn more.

Neil Bartlett and the Reactive Noble Gases

University of British Columbia | Vancouver, Canada

Science is frequently a collaborative discipline. But sometimes, one person, working alone, makes a stunning discovery that changes a scientific field forever. Neil Bartlett, while working alone in his laboratory, demonstrated that the "inertness" of the Group VIII elements was not a fundamental law of nature as previously believed. Bartlett's discovery meant that all existing textbooks had to be rewritten. Today, compounds of the noble gases are used in a variety of applications, including in lasers and to create anti-tumor agents. Learn more.

Separation of Rare Earth Elements by Charles James

University of New Hampshire | Durham, New Hampshire

Charles James, a chemistry professor at the University of New Hampshire from 1906 to 1928, was an internationally-recognized expert in rare earth chemistry. In a laboratory in Conant Hall, James devised novel fractional crystallization techniques for separating rare earth elements, which were widely adopted by other chemists. James used his method to separate large amounts of ytterbium, previously considered to be a single element, into two elements now known as ytterbium and lutetium. Learn more.